<template>
  <div id="home">
    <nav-bar class="home-nav">
      <div slot="center">购物街</div>
    </nav-bar>

    <tab-control :titles="['流行','新款','精选']" @tabClick="tabClick" ref="tabControl1" class="tab-control" v-show="isTabFixed" />

    <scroll class="content" ref="scroll" :probe-type="3" @scroll="contentScroll" :pull-up-load="true" @pullingUp="loadMore">
      <home-swiper :banners="banners" @swiperImageLoad="swiperImageLoad" />
      <home-recommend-view :recommends="recommends" />
      <home-feature-view />
      <tab-control :titles="['流行','新款','精选']" @tabClick="tabClick" ref="tabControl2" />
      <goods-list :goods="showGoods" />
    </scroll>

    <back-top @click.native="backTop" v-show="isShowBackTop" />
  </div>
</template>

<script>
import HomeSwiper from "./childComps/HomeSwiper"
import HomeRecommendView from "./childComps/HomeRecommendView"
import HomeFeatureView from "./childComps/HomeFeatureView"

import NavBar from "components/common/navbar/NavBar"
import Scroll from "components/common/scroll/Scroll"
import TabControl from "components/content/tabControl/TabControl"
import GoodsList from "components/content/goods/GoodsList"
import BackTop from "components/content/backTop/BackTop"

import { getHomeMultidata, getHomeGoods } from "network/home"
import { debounce } from "common/utils/Utils"

export default {
  name: "Home",
  components: {
    NavBar,
    HomeSwiper,
    HomeRecommendView,
    HomeFeatureView,
    TabControl,
    GoodsList,
    Scroll,
    BackTop
  },
  data() {
    return {
      banners: [],
      recommends: [],
      goods: {
        "pop": { page: 0, list: [] },
        "new": { page: 0, list: [] },
        "sell": { page: 0, list: [] }
      },
      currentType: "pop",
      isShowBackTop: false,
      tabOffsetTop: 0,
      isTabFixed: false,
      saveY: 0
    }
  },
  created() {
    //请求多个数据
    this.getHomeMultiData();

    //请求商品数据
    this.getHomeGoodsData("pop");
    this.getHomeGoodsData("new");
    this.getHomeGoodsData("sell");
  },
  mounted() {
    //监听GoodsListItem中图片加载完成
    //调用防抖函数
    const refresh = debounce(this.$refs.scroll.refresh, 300);
    this.$bus.$on("itemImageLoad", () => {
      refresh();
    })
  },
  activated() {
    this.$refs.scroll.scrollTo(0, this.saveY, 0);
    this.$refs.scroll.refresh();
  },
  deactivated() {
    this.saveY = this.$refs.scroll.getScrollY();
  },
  computed: {
    showGoods() {
      return this.goods[this.currentType].list;
    }
  },
  methods: {

    /*
    * 关于事件监听
    */
    tabClick(index) {
      switch (index) {
        case 0: this.currentType = "pop";
          break;
        case 1: this.currentType = "new";
          break;
        case 2: this.currentType = "sell";
          break;
      }
      this.$refs.tabControl1.currentIndex = index;
      this.$refs.tabControl2.currentIndex = index;
    },

    backTop() {
      this.$refs.scroll.scrollTo(0, 0, 500);
    },

    contentScroll(position) {
      //判断BackTop是否显示
      this.isShowBackTop = (-position.y) > 1000;

      //决定tabControl是否吸顶（position:fixed）
      this.isTabFixed = (-position.y) > this.tabOffsetTop;
    },

    //上拉加载更多
    loadMore() {
      this.getHomeGoodsData(this.currentType);
    },

    swiperImageLoad() {
      //获取tabControl的offsetTop
      //所有的组件都有一个属性$el：用于获取组件中的元素
      this.tabOffsetTop = this.$refs.tabControl2.$el.offsetTop;
    },

    /*
    * 关于网络请求
    */
    getHomeMultiData() {
      getHomeMultidata().then(res => {
        this.banners = res.data.banner.list;
        this.recommends = res.data.recommend.list;
      })
    },
    getHomeGoodsData(type) {
      const page = this.goods[type].page + 1;
      getHomeGoods(type, page).then(res => {
        // ... 将res.data.list中的数据一个一个的解析出来，push到goods中对应的对象里
        this.goods[type].list.push(...res.data.list);
        this.goods[type].page += 1;

        this.$refs.scroll.finishPullUp();
      })
    }
  }
}
</script>

<style scoped>
#home {
  /* padding-top: 44px; */
  height: 100vh;
  position: relative;
}

.home-nav {
  background-color: var(--color-tint);
  color: #fff;

  /* 在使用浏览器原生滚动时，为了让导航栏不跟随一起滚动 */
  /* position: fixed;
  left: 0;
  right: 0;
  top: 0;
  z-index: 9; */
}

.content {
  overflow: hidden;

  position: absolute;
  top: 44px;
  bottom: 49px;
  left: 0;
  right: 0;
}

.tab-control {
  position: relative;
  z-index: 9;
}

/* .content {
height: calc(100% - 93px);
overflow: hidden;
margin-top: 44px;
} */
</style>
